Sintered neodymium-iron-boron magnet and preparation method thereof

Abstract

The invention provides a sintered neodymium-iron-boron magnet and a preparation method thereof. The preparation method comprises the following steps: S10, preparing a plurality of blank magnetic steels; s20, the blank magnetic steel is stacked, and a dielectric layer is arranged between every two adjacent blank magnetic steel; s30, acting on the dielectric layer in a metal bonding mode to connect the adjacent blank magnetic steel into a whole to obtain a sintered neodymium-iron-boron magnet; wherein the magnetization direction of the blank magnetic steel and the dielectric layer form any angle; the metal bonding principle is welding. According to the method, through the metal bonding mode of the welding principle, the blank magnetic steel is connected more firmly, the problem that in a traditional method, the structure is not uniform possibly is solved, and the mechanical strength and stability of the sintered neodymium-iron-boron magnet are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic material preparation, and in particular, to a sintered neodymium iron boron magnet and a preparation method thereof. Background Art

[0002] Sintered neodymium iron boron is widely used in many fields such as aerospace, electronic communication, clean energy, transportation, medical devices, and household appliances due to its excellent magnetic properties. With the development of technology, the demand for complex magnetic field environments is increasing day by day, especially in application scenarios that require non-single magnetic orientation.

[0003] At present, for sintered neodymium iron boron component products with complex magnetic orientation, chemical glue bonding or mechanical fixing processes are mainly used. However, these traditional methods have many defects. When using chemical glue bonding, the mechanical strength of the product is insufficient, the bonding size discreteness is relatively large, and there are problems in terms of environmental tolerance and electroplating during use. These defects may lead to a decline in the performance and a shortening of the lifespan of the product in actual applications. On the other hand, the mechanical fixing process requires fixing the magnet by means of screws or card slots, which requires counterbore holes or special-shaped processing of the magnet. This kind of processing not only causes a loss of effective magnetic properties but also makes its application in micro-sized products difficult. Especially in applications that require precise control of the magnetic field, this kind of processing may significantly affect the performance and accuracy of the magnet.

[0004] Therefore, the existing preparation methods are difficult to directly prepare magnet components with specific magnetic fields, various shapes, and functions, which limits the use of sintered neodymium iron boron magnets in some high-end application fields and also increases the complexity and cost of the production process. Summary of the Invention

[0005] The purpose of the present invention is to provide a sintered neodymium iron boron magnet and a preparation method thereof, which have the advantages of improving the mechanical strength of the magnet component, improving the dimensional accuracy, enhancing the environmental tolerance, avoiding the loss of effective magnetic properties, being applicable to micro-sized products, and realizing a complex magnetic field structure.

[0006] To achieve the above purpose, the present invention provides a preparation method of a sintered neodymium iron boron magnet. The preparation method includes the following steps: S10: Prepare a number of blank magnetic steels; S20: Stack the blank magnetic steels, and a dielectric layer is provided between adjacent blank magnetic steels; S30: Use a metal bonding method to act on the dielectric layer to connect adjacent blank magnetic steels into one body to obtain a sintered neodymium iron boron magnet; wherein, the magnetization direction of the blank magnetic steel forms an arbitrary angle with the dielectric layer; the principle of metal bonding is welding.

[0007] Furthermore, the dielectric layer is a deposited metal; wherein, the deposited metal includes at least one of the elements Al, Cu, Sn, Ti, Mg, Cr, Ni, Zn, Ag, Au and their alloys.

[0008] Further, the thickness of the dielectric layer before metal bonding is 1 µm - 100 µm.

[0009] Further, S20 specifically includes: electroplating the dielectric layer onto the surface of the blank magnet, stacking the blank magnets, and arranging the dielectric layer between adjacent blank magnets; wherein, the dielectric layer includes at least two of the elements Al, Cu, Sn, Ti, Mg, Cr, Ni, Zn, Ag, Au and their alloys.

[0010] Further, S30 specifically includes: performing a welding process on the dielectric layer to connect adjacent blank magnets into one body, and then performing an electroplating process on its surface to obtain a sintered neodymium iron boron magnet; wherein, the dielectric layer includes at least one of the elements Al, Cu, Sn, Ti, Mg, Cr, Ni, Zn, Ag, Au and their alloys.

[0011] Further, the processing conditions for metal bonding include: performing a welding process on the dielectric layer under a temperature condition of 150°C - 950°C and a pressure condition of 50 N - 500 N.

[0012] Further, there is a bonding spacing between adjacent blank magnets, and the bonding spacing is 20 µm - 100 µm.

[0013] Further, the shape of the blank magnet includes at least one of circular, annular, polygonal, semi - arc - shaped, and irregular.

[0014] The present invention also provides a sintered neodymium iron boron magnet, which is prepared by the preparation method as described above.

[0015] Further, the magnet arrangement of the sintered neodymium iron boron magnet includes a Halbach array.

[0016] After adopting the technical solution of the present invention, the following technical effects can be achieved: (1) Improving the mechanical properties and stability of the magnet: By means of metal bonding, the connection between blank magnets is made more firm, avoiding the problem of uneven structure that may occur in the traditional method, and improving the mechanical strength and stability of the sintered neodymium iron boron magnet; (2) Flexible adjustment of the magnetization direction: Since there is no requirement for a fixed angle between the magnetization direction and the dielectric layer, the magnetization direction of the magnet can be adjusted in different applications, thus meeting the requirements under different application scenarios and increasing the design freedom of the magnet; (3) Improving production efficiency and reducing material waste: By stacking and metal - bonding adjacent blank magnets, some energy losses and material waste in the traditional sintering process can be reduced, improving the overall production efficiency and reducing production costs; (4) Improve the performance of the magnet: The metal bonding method using welding technology can effectively enhance the magnetism, corrosion resistance and anti-aging property of the NdFeB magnet, so that it can maintain good working performance under different environmental conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which: Figure 1 FIG. is a process flow chart of the sintered NdFeB magnet provided by the embodiment of the present invention; Figure 2 FIG. shows NdFeB magnets with different orientations and shapes provided by Embodiment 1 of the present invention; Figure 3 FIG. shows NdFeB magnets with different orientations and shapes provided by Comparative Example 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0019] As Figure 1 shown, the embodiment of the present invention provides a preparation method of a sintered NdFeB magnet. The preparation method includes the following steps: S10: Prepare a plurality of blank magnets; S20: Stack the blank magnets, and a dielectric layer is provided between adjacent blank magnets; S30: Apply a metal bonding method to the dielectric layer to connect adjacent blank magnets into one body to obtain a sintered NdFeB magnet; wherein, the magnetization direction of the blank magnet forms an arbitrary angle with the dielectric layer; the principle of metal bonding is welding.

[0020] This embodiment provides a preparation method of a sintered NdFeB magnet. Among them, the prefabricated blank magnets are stacked in a specific manner, and a dielectric layer is placed between adjacent blank magnets. The dielectric layer may play a role of separation and isolation here, which can control and optimize the physical and chemical properties between the magnets in subsequent operations. Further, adjacent blank magnets are connected by a metal bonding method. The presence of the dielectric layer and the application of the metal bonding technology make adjacent magnet particles bond into one body at high temperature through a metal material according to the principle of welding, and finally form a sintered NdFeB magnet. In addition, the magnetization direction of the blank magnet forms an arbitrary angle with the dielectric layer, which helps to improve the overall performance of the magnet and adjust its magnetic characteristics.

[0021] By metal bonding, the connection between the blank magnets is made stronger, avoiding the problem of structural unevenness that may occur in traditional methods, and improving the mechanical strength and stability of the sintered NdFeB magnets. Since there is no fixed angle requirement between the magnetization direction and the dielectric layer, the magnetization direction of the magnet can be adjusted in different applications to meet the needs of different application scenarios and increase the design freedom of the magnet. By stacking and metal bonding adjacent blank magnets, some energy loss and material waste in the traditional sintering process can be reduced, the overall production efficiency can be improved, and the production cost can be reduced. The welding technology based on the metal bonding principle can effectively improve the magnetism, corrosion resistance and aging resistance of NdFeB magnets, so that they can maintain good working performance under different environmental conditions.

[0022] Preferably, after the stacked blank magnets are connected as a whole by metal bonding, the surface of the magnets is electroplated to finally obtain a sintered NdFeB magnet. Preferably, a NiCuSn layer can be electroplated on the surface of the blank magnets, and then the blank magnets are stacked for bonding.

[0023] In some embodiments of the present application, the dielectric layer is a deposited metal; wherein the deposited metal includes at least one of Al, Cu, Sn, Ti, Mg, Cr, Ni, Zn, Ag, Au single substances and alloys thereof.

[0024] By using deposited metal as the dielectric layer, the mechanical strength of welding can be improved and the discreteness of bonding size can be reduced. The selection range of deposited metals is wide, including a variety of single substances and alloys. These metal materials can provide good bonding performance and mechanical strength during the welding process. By using deposited metal as the dielectric layer and welding, the problems of mechanical strength and discreteness of bonding size of metal bonding in the preparation process of sintered NdFeB magnets can be effectively solved. It should be noted that the blank magnetic steel and other various soft magnetic materials, rare earth permanent magnetic materials, and even any other materials can be welded.

[0025] The deposited metal can be deposited on the surface of the rough magnetic steel by electroplating, chemical vapor deposition, physical vapor deposition and other methods. These methods can ensure the uniformity and adhesion of the deposited metal layer, thereby ensuring the welding quality. Selecting a variety of metal elements and their alloys as deposited metals makes the technical solution highly adaptable and can meet the welding requirements of different metal substrates. For example, using aluminum alloy or titanium alloy as the deposited metal can effectively deal with the high-temperature welding problems associated with these metals. Preferably, the surface of the rough magnetic steel is cleaned before the deposition of the deposited metal. Preferably, the magnetic steel in the relatively middle part can be weakly magnetized to better fix the magnetic steel on the upper and lower sides.

[0026] In some embodiments of the present application, the thickness of the dielectric layer before metal bonding is 1 µm - 100 µm.

[0027] When metal bonding is carried out by welding, by controlling the thickness of the deposited metal between 1 µm - 100 µm, it ensures that the thickness of the dielectric layer is appropriate during the welding process, thereby improving the bonding strength and reliability of the sintered NdFeB magnet.

[0028] Specifically, controlling the thickness of the deposited metal between 1 µm - 100 µm can be achieved in various ways. For example, electroplating technology can be used, and the thickness of the deposited metal can be precisely controlled by controlling the electroplating time and current density. Physical vapor deposition or chemical vapor deposition technology can also be used, and precise thickness control can be achieved by controlling the deposition time and gas flow rate. Further, by the method of multi-layer deposition, thickness measurement and adjustment are carried out between each layer to ensure that the final thickness is between 1 µm - 100 µm. These methods can effectively ensure that the thickness of the deposited metal is within the specified range, thereby ensuring that the thickness of the dielectric layer is appropriate during the welding process, avoiding the situation of weak bonding due to too thin a metal layer and coating peeling or cracking due to too thick a metal layer.

[0029] It should be noted that during the metal bonding process, welding metal is required to achieve welding, and the thickness of the dielectric layer before metal bonding does not include the thickness of the metal used for welding.

[0030] In some embodiments of the present application, S20 specifically includes: electroplating the dielectric layer onto the surface of the blank magnet steel, stacking the blank magnet steels, and the dielectric layer is disposed between adjacent blank magnet steels; wherein, the dielectric layer includes at least two of the elements Al, Cu, Sn, Ti, Mg, Cr, Ni, Zn, Ag, Au and their alloys.

[0031] The dielectric layer can improve the bonding strength between adjacent blank magnet steels, making the stacked and welded magnet more firm, preventing it from falling off or loosening during use, and ensuring the stability and reliability of the magnet. In addition, by electroplating the dielectric layer on the surface of the blank magnet steel, its surface roughness and wear resistance can be improved, providing a better interface for the stacking process. By selecting a variety of metal elements and their alloys as the dielectric layer material, the electroplating material can be flexibly adjusted according to different application requirements and environmental conditions to meet different magnet performance requirements. For example, in applications requiring high conductivity, copper or silver can be selected, while in applications requiring corrosion resistance, aluminum or nickel can be selected.

[0032] In addition, the electroplating process of the dielectric layer can more precisely control the thickness of the material, reduce waste, and improve the material utilization rate. Preferably, a NiCuSn layer can be electroplated on the surface of the blank magnet steel, and then the blank magnet steels can be stacked for bonding operations.

[0033] In some embodiments of the present application, S30 specifically includes: performing a welding process on the dielectric layer to connect adjacent blank magnets into one body, and then performing an electroplating process on its surface to obtain a sintered neodymium iron boron magnet; wherein, the dielectric layer includes at least one of the elements Al, Cu, Sn, Ti, Mg, Cr, Ni, Zn, Ag, Au and their alloys.

[0034] Performing electroplating after welding can significantly improve the corrosion resistance and oxidation resistance of the magnet surface. This means that in a harsh environment, the sintered neodymium iron boron magnet can maintain a long service life and stable performance, reducing performance degradation caused by corrosion or surface damage. By combining the methods of welding and electroplating, multiple blank magnets can be effectively combined into a complete magnet structure, while ensuring good surface quality of each magnet, further improving the overall magnetism and mechanical strength of the sintered neodymium iron boron magnet.

[0035] Compared with the prior art, the metal medium can be covered by the plating layer during electroplating, and the salt spray ability of a single magnet can be achieved without worrying about the shedding during glue bonding; the conductivity of the metal medium enables products bonded with the metal medium not to affect the electroplating effect of the finished product, while magnet components bonded with ordinary glue cannot be electroplated.

[0036] The dielectric layer can use a variety of metal materials or their alloys, which can be flexibly selected according to different requirements, and can meet the requirements for magnet performance, cost, corrosion resistance, etc. in different application scenarios. The combined process of welding and electroplating is relatively simple, has a low cost, and has a high production efficiency. The electroplating process can precisely control the thickness of the metal layer and reduce material waste, thereby reducing the production cost and improving the economic benefits of production.

[0037] It should be noted that in step S20, electroplate the dielectric layer onto the surface of the blank magnet and then perform welding, and in step S30, weld the blank magnets provided with the dielectric layer into one body and then perform electroplating on its surface. Either of the above two metal bonding methods can be selected.

[0038] In some embodiments of the present application, the processing conditions for metal bonding include: performing a welding process on the dielectric layer under a temperature condition of 150°C - 950°C and a pressure condition of 50N - 500N.

[0039] The dielectric layer is processed by welding, specifically under the temperature condition of 150°C - 950°C and the pressure condition of 50N - 500N. This feature plays an important role in solving the problems of temperature and pressure treatment during the welding process of sintered NdFeB magnets. By performing the welding treatment under specific temperature and pressure conditions, effective connection of the dielectric layer can be achieved, ensuring the mechanical strength and stability of the sintered NdFeB magnet, thereby improving the performance and reliability of the product.

[0040] During the welding process, the material of the dielectric layer can be deposited metal, and the thickness of the deposited metal is 1µm - 100µm. The welding temperature range is 150°C - 950°C, and the pressure range is 50N - 500N. Specifically, the selection of welding temperature and pressure should be optimized according to the actual material and usage environment to ensure the best state of welding effect and magnet performance. For example, at higher temperatures and pressures, the welding time can be correspondingly shortened, while at lower temperatures and pressures, the welding time may need to be extended to ensure sufficient connection of the dielectric layer. In addition, different deposited metal materials may exhibit different characteristics during the welding process and need to be adjusted and optimized according to the actual situation.

[0041] In some embodiments of the present application, there is an adhesive spacing between adjacent blank magnets, and the adhesive spacing is 20µm - 100µm.

[0042] By setting a specific adhesive spacing between adjacent blank magnets and ensuring that the adhesive spacing is within the range of 20µm - 100µm, the adhesive effect of the blank magnets can be effectively controlled, and the adhesion between the blank magnets can also be ensured to have consistency and stability, thereby improving the overall performance and reliability of the sintered NdFeB magnet.

[0043] It should be noted that after the metal bonding is completed, since welding metal is used to achieve welding during the welding process, the thickness of the dielectric layer after metal bonding is greater than the thickness of the dielectric layer before metal bonding. Among them, the thickness of the dielectric layer after metal bonding is equal to the adhesive spacing between the two blank magnets.

[0044] The setting of the adhesive spacing can be achieved through precise machining or precise positioning devices to ensure that the spacing between each blank magnet meets the requirements during the production process. Specifically, high-precision spacing control equipment such as a laser locator or a high-precision mechanical fixture can be used. In addition, the spacing can also be controlled by adjusting the thickness of the adhesive material or the adhesive process parameters. For example, during the bonding process, by controlling the coating thickness of the adhesive material and the pressure during the curing process, the final adhesive spacing can be accurately controlled.

[0045] In addition, precise control of the bonding spacing between adjacent blank magnets can optimize the magnetic properties of the magnets after assembly. Too small a bonding spacing may lead to excessive contact between the magnets, thereby affecting the distribution of the magnetic field and causing magnetic force attenuation; while too large a spacing may lead to reduced magnetic force conduction efficiency between the magnets. By controlling between 20µm and 100µm, these two situations can be effectively avoided to ensure the optimization of the magnetic field effect between the magnets. On the other hand, a reasonable bonding spacing can improve the firmness of the bonding between the magnets, avoid uneven bonding or falling off caused by too large or too small a spacing, help improve the stability and service life of the overall assembly, and reduce the defective rate in production.

[0046] In some embodiments of the present application, the shape of the rough magnetic steel includes at least one of a circle, a ring, a polygon, a semi-arc and an irregular shape.

[0047] By stipulating that the shape of the blank magnetic steel can be at least one of a circle, a ring, a polygon, a semi-arc and an irregular shape, the problem of the diversified shapes of sintered NdFeB magnets in the preparation process is solved. The diversity of these shapes makes the application of magnet components in complex magnetic field environments more flexible, meets different application requirements, and improves production efficiency and controllability of magnet performance.

[0048] The shape of the blank magnet can be selected and designed according to the specific application requirements. For example, in applications that require circular magnets, circular blank magnets can be selected; in applications that require ring magnets, annular blank magnets can be selected; in applications that require magnets with complex geometric shapes, polygonal, semi-arc or irregular blank magnets can be selected. Blank magnets of these different shapes can be realized by mold forming, machining and the like. Furthermore, sintered NdFeB magnets can be composed of 5, 7 or more blank magnets bonded together.

[0049] An embodiment of the present invention further provides a sintered NdFeB magnet, which is prepared by the preparation method described above.

[0050] The present application proposes a sintered NdFeB magnet by adopting the aforementioned preparation method. The magnet introduces new procedures and technologies in the preparation process, and can directly prepare magnet components with specific magnetic fields, various shapes and functions. Through the mutual cooperation of these technical features, the application requirements of sintered NdFeB magnets in complex magnetic field environments can be met, and the production efficiency and controllability of magnet performance can be improved. In the present application, the dielectric layer between the rough steel magnets is processed by grain boundary diffusion or welding, so that adjacent rough steel magnets can be firmly connected together, and finally a sintered NdFeB magnet is formed.

[0051] In some embodiments of the present application, the magnet arrangement of the sintered neodymium iron boron magnet includes a Halbach array.

[0052] The Halbach array is a special magnet arrangement. By cleverly arranging permanent magnets, the magnetic field is enhanced in some areas of the array while weakened or disappeared in other areas. Generally, the arrangement of the Halbach array can concentrate the magnetic field in a specific direction or area, greatly improving the directivity and efficiency of the magnetic field. The application of the Halbach array can reduce the number of magnets and optimize the distribution of the magnetic field, which is of great significance in applications that require efficient magnetic field directivity, such as magnetic levitation, brushless motors, sensors, etc.

[0053] Using the Halbach array as the arrangement of the sintered neodymium iron boron magnet means that during the preparation process, the neodymium iron boron magnet will be arranged according to the specific arrangement of the Halbach array. This arrangement enables the magnet to generate stronger magnetic field directivity and control force during use, thereby improving its overall performance without increasing the number of magnets.

[0054] It should be noted that the sintered neodymium iron boron magnet provided by this technical solution is applicable to the bonding of all Halbach magnetic circuits, but not limited to the Halbach array. The magnet arrangement of the sintered neodymium iron boron magnet also includes arrays of other non-Halbach magnetic circuits.

[0055] Example 1 The embodiment of the present invention provides a preparation method of a sintered neodymium iron boron magnet, including the following steps: S1. Prepare a strip casting by melting the components of PrNd 30 Co1Cu 0.15 Al 0.2 Ga 0.2 Ti 0.2 Zr 0.2 B 0.92 Fe 余 Then, through hydrogen decrepitation, jet milling, compacting, and sintering in sequence, a blank magnet steel with a size of 3mm × 2mm × 3mm is prepared; S2. Process the blank magnet steel with different orientations and shapes according to the required complex magnetic field; stack the processed blank magnet steels from top to bottom in sequence, and deposit a Cu film with a thickness of 1 µm - 100 µm on the contact surfaces of the blank magnet steels that need to be bonded; S3. Adopt a welding method to uniformly weld the stacked blank magnet steels with Sn at 150°C - 950°C along the surface of the Cu film, and then electroplate to finally obtain a sintered neodymium iron boron magnet with a size of 3mm × 3mm × 6mm, where the bonding spacing between adjacent blank magnet steels is 20 µm - 100 µm.

[0056] Figure 2 The NdFeB magnets with different orientations and shapes provided in Embodiment 1 of the present invention.

[0057] Comparative Example 1 An embodiment of the present invention provides a preparation method of a sintered NdFeB magnet, comprising the following steps: S1. Prepare a strip casting by melting components of PrNd 30 Co1Cu 0.15 Al 0.2 Ga 0.2 Ti 0.2 Zr 0.2 B 0.92 Fe 余 Prepare a blank magnet steel with a size of 3mm×2mm×3mm after strip casting, hydrogen decrepitation, jet milling, compacting and sintering in sequence; S2. Process the blank magnet steel with different orientations and shapes according to the required complex magnetic field; stack the processed blank magnet steels from top to bottom in sequence; S3. Bond and electroplate the stacked blank magnet steels in the way of grain boundary diffusion, and finally obtain a sintered NdFeB magnet with a size of 3mm×3mm×6mm.

[0058] Comparative Example 2 The comparative example of the present invention provides a preparation method of a sintered NdFeB magnet, comprising the following steps: S1. Prepare a strip casting by melting components of PrNd 30 Co1Cu 0.15 Al 0.2 Ga 0.2 Ti 0.2 Zr 0.2 B 0.92 Fe 余 Prepare a blank magnet steel with a size of 3mm×2mm×3mm after strip casting, hydrogen decrepitation, jet milling, compacting and sintering in sequence; S2. Process the blank magnet steel with different orientations and shapes according to the required complex magnetic field; stack the processed blank magnet steels from top to bottom in sequence; S3. Bond the stacked blank magnet steels in the way of glue bonding, and finally obtain a NdFeB magnet with a size of 3mm×3mm×6mm.

[0059] Figure 3 The NdFeB magnets with different orientations and shapes provided in Comparative Example 2 of the present invention.

[0060] Test results: For the sintered NdFeB magnets obtained by the preparation methods of the above-mentioned Example 1 and Comparative Examples 1-2, their basic properties were respectively tested, such as the surface magnetic attenuation of the center point, dimensional deviation, mechanical properties, water immersion resistance and salt spray resistance. Table 1 shows the basic property test results of the sintered NdFeB magnets of Example 1 and Comparative Examples 1-2.

[0061] Table 1 Basic property test results of the sintered NdFeB magnets of Example 1 and Comparative Examples 1-2 It can be seen from the surface magnetic attenuation of the center point of the sintered NdFeB magnet that through the preparation method provided by this embodiment, not only the temperature resistance of the magnet is greatly improved, but also the shear strength, water immersion resistance and dimensional deviation of the magnet have been significantly improved. This is because through the present invention, in a microgravity environment, the metal medium enters the grain boundary phase along the Nd-rich phase, improving the distribution and wettability of the Nd-rich phase, thereby increasing the Hcj of the magnet and improving the temperature resistance of the magnet. At the same time, the metal medium is used to connect the Nd-rich phases of adjacent magnets to form a whole; the different orientations of the Halbach permanent magnet result in repulsive forces, so that the acrylic glue may generally come off within 24h-48h. Due to the unique metal properties of metal bonding, water molecules are difficult to break the metal bond, and short-term immersion tests have little effect on it; by using the metal bonding process, conventional magnet processing (such as cutting, grinding, chamfering, etc.) can be carried out after bonding, making its dimensional accuracy the same as that of a single magnet, avoiding the accumulation of assembly tolerances and solving the problem of inconsistent dimensions due to glue bonding.

[0062] Comparative Example 1 is a bonding process in the prior art, and the bonding process provided by Example 1 of the present invention is easier to operate than Comparative Example 1. Further, in Example 1, by using the welding of low-melting-point metals and adding deposition and welding processes in the black sheet process, since the metal medium has good mechanical strength, the shear strength of the magnets bonded together is also increased, so that the same effect as Comparative Example 1 can be achieved without affecting the magnet performance.

[0063] Meanwhile, the medium metal can be covered by the coating during electroplating, achieving the salt spray resistance of a single magnet without worrying about detachment during glue bonding. The conductivity of the metal medium enables products bonded with the metal medium not to affect the electroplating effect of the finished product. For magnetic components bonded with ordinary glue, electroplating coatings cannot be applied due to the glue. Products bonded with the metal medium have the possibility of multiple coating selections. Finally, by using the method of Embodiment 1, magnets can also be welded together with various other soft magnetic materials, rare earth permanent magnetic materials, or even any other materials. This sintered neodymium iron boron metal bonding process compensates for many deficiencies of the traditional bonding process, thus enabling the preparation of Balback magnet components with various shapes and functions. However, by using the method of Comparative Example 1, only the blank magnetic steel can be metal-bonded with other permanent magnetic materials that do not include soft magnets and ferrites, which has certain limitations.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A preparation method of a sintered neodymium iron boron magnet, characterized in that, The preparation method includes the following steps: S10: Prepare a number of blank magnets; S20: Stack the blank magnets, and a dielectric layer is provided between adjacent blank magnets; S30: Apply metal bonding to the dielectric layer to connect adjacent blank magnets into one body, obtaining the sintered neodymium iron boron magnet; Wherein, the magnetization direction of the blank magnet forms an arbitrary angle with the dielectric layer; the principle of the metal bonding is welding.

2. The preparation method according to claim 1, characterized in that, The dielectric layer is a deposited metal; wherein, the deposited metal includes at least one of the elements Al, Cu, Sn, Ti, Mg, Cr, Ni, Zn, Ag, Au and their alloys.

3. The preparation method according to claim 1, characterized in that, The thickness of the dielectric layer before the metal bonding is 1 µm - 100 µm.

4. The preparation method according to claim 1, characterized in that, The S20 specifically includes: Electroplate the dielectric layer onto the surface of the blank magnet, and stack the blank magnets, with the dielectric layer provided between adjacent blank magnets; Wherein, the dielectric layer includes at least two of the elements Al, Cu, Sn, Ti, Mg, Cr, Ni, Zn, Ag, Au and their alloys.

5. The preparation method according to claim 1, characterized in that, The S30 specifically includes: Perform welding treatment on the dielectric layer to connect adjacent blank magnets into one body, and then perform electroplating treatment on its surface to obtain the sintered neodymium iron boron magnet; Wherein, the dielectric layer includes at least one of the elements Al, Cu, Sn, Ti, Mg, Cr, Ni, Zn, Ag, Au and their alloys.

6. The preparation method according to claim 1, characterized in that, The processing conditions of the metal bonding include: Perform welding treatment on the dielectric layer under the temperature condition of 150°C - 950°C and the pressure condition of 50 N - 500 N.

7. According to the preparation method described in claim 1, characterized in that There is a bonding spacing between adjacent blank magnets, and the bonding spacing is 20 µm - 100 µm.

8. According to the preparation method described in claim 1, characterized in that The shape of the blank magnet includes at least one of circular, ring-shaped, polygonal, semi-circular and irregular shapes.

9. A sintered neodymium iron boron magnet, characterized in that, The sintered neodymium iron boron magnet is prepared by the preparation method described in any one of claims 1 - 8.

10. The sintered neodymium iron boron magnet according to claim 9, wherein, The magnet arrangement of the sintered neodymium iron boron magnet includes a Halbach array.

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